<template>
    <div id="list-demo" class="demo">
    <button v-on:click="add">Add</button>
    <button v-on:click="remove">Remove</button>
    <transition-group name="list" tag="p">
        <span v-for="item in items" v-bind:key="item" class="list-item">
        {{ item }}
        </span>
    </transition-group>
    </div>
</template>

<script>
export default {
   name:'TransitionTest',
   data() {
       return {
            items: [1,2,3,4,5,6,7,8,9],
            nextNum: 10
       };
   },
   methods: {
        randomIndex: function () {
            return Math.floor(Math.random() * this.items.length)
        },
        add: function () {
            this.items.splice(this.randomIndex(), 0, this.nextNum++)
        },
        remove: function () {
            this.items.splice(this.randomIndex(), 1)
        },
   },
   mounted() {
       
   },
}
</script>
<style lang='less' scoped>
.list-item {
  display: inline-block;
  padding: 0 5px;
}
.list-enter-active, .list-leave-active {
  transition: all 1s;
}
.list-enter, .list-leave-to
/* .list-leave-active for below version 2.1.8 */ {
//   opacity: 0;
  transform: scaleX(0);
}
</style>